Apparent diffusion coefficient (ADC): A potential in vivo biological surrogate of the incidentally discovered bone lesions at 3T MRI

Purpose: To probe the potential of apparent diffusion coefficient (ADC) to rectify the incidentally detected bone lesion on MRI into benign or malignant lesions. Materials and methods: We retrospectively recruited 44 patients (24 males and 20 females); with 52 bone lesions, who underwent diffusion weighted (DW) imaging using multiple b-values on 3 T MRI. ADC maps were derived and analyzed by two radiologists; blinded to the final diagnosis. The mean ADC values were used for statistical analyses. The diagnosis was deduced by histopathological confirmation; in 32 lesions and strict clinical and imaging follow-up for at least 12 months; in 20 lesions. Results: The mean ADC value (mean +/- SD) of all malignant tumors (including cartilaginous neoplasms) was [0.92 +/- 0.40] x 10(3) mm(2)/s. This significantly differed from those of both primary benign tumors [1.14 +/- 0.24] x 10(3) mm(2)/s, (p = 0.011), and all non-malignant lesions collectively [1.29 +/- 0.44] x 10(3) mm(2)/s, (p < 0.001). Using mADC value of <= 1.1 x 10(-3) mm(2)/s resulted in 86.1% sensitivity and 62.5% specificity for characterizing a lesion as a malignant. The inter-rater reliability was almost perfect (95% CI = 0.954-0.985). Conclusion: ADC could be a non-invasive in-vivo surrogate that may be able to discern the incidentally discovered osseous lesions into benign and malignant pathologies and guide further diagnostic workup.